Apparatus for improving the reaction between two liquids of different specific gravities

ABSTRACT

A method of improving the reaction between two liquids of different specific gravities such as between a metallurgical melt and a slag layer covering it comprises producing a flow in the reaction zone between the two liquids of different specific gravities such that the liquid of high specific gravity, for example, the melt is circulated in the vessel and guided substantially radially outwardly in the reaction zone whereas the liquid of low specific gravity, for example, the slag, is conveyed in a circulation from the periphery inwardly in substantially opposite direction to that of the high specific gravity liquid. A device for carrying out the method includes two pumping elements, one of which takes suction at the lower end of the liquid of high specific gravity and circulates this liquid upwardly to the reaction zone in the vicinity of the level of the liquid of low specific gravity and directs outwardly toward the outer periphery of the reaction zone. A second pumping element is arranged to take suction at the outer periphery of the liquid of low specific gravity and to direct it inwardly at a location adjacent the level of the high specific gravity. A pump construction for this purpose may advantageously include a single rotor mounting an impeller having an elongated cylindrical suction extending downwardly into the high specific gravity melt and an upper portion extending radially outwardly and having peripheral openings for discharging the high specific gravity liquid radially outwardly. The same pump shaft also carries an impeller at the upper end having vane elements which are curved in a formation for moving the low specific gravity liquid inwardly and for discharging it toward the center. The low specific gravity pumping impellers may advantageously be formed as blade elements on the top of the impeller for pumping the high specific gravity liquid.

United States Patent [72] lmentor Jan-Erik Ostberg Bettna, Sweden [21] Appl. No. 673,542 [22 Filed Oct. 9, 1967 [45] Patented Jan. 12, 1971 [32] Priority Oct. .I, 1966 [33] Germany [31 l 0 12,013

[54] APPARATUS FOR IMPROVING THE REACTION BETWEEN TWO LIQUIDS OF DIFFERENT SPECIFIC GRAVITIES l 1 Claims, 3 Drawing Figs. 5

[52] US. Cl 266/34,

75/50, 75/61 [51] Int. Cl C2lc 7/00, C2lc 7/10 [50] Field ofSearch 75/45, 50, 61, 93; 266/34A, 34

[56] References Cited UNITED STATES PATENTS 2,397,737 4/1946 Hever 75/55 1,740,752 12/1929 Thompson .266/ 34X 2,195,092 3/1940 Muller et a]. 266/34 2,290,961 7/ 1942 l-lever 75/49UX 2,660,525 1 1/1953 Foster 266/34X 3,015,554 l/1962 Rummel 75/51 3,278,295 10/1966 Ostberg et al 75/93 FOREIGN PATENTS 22,276 6/1912 Norway 266/34 II IQ Primary ExaminerL. Dewayne Rutledge Assistant ExaminerG.K. White An0rneyMcGlew and Toren ABSTRACT: A method of improving the reaction between two liquids of difi'erent specific gravities such as between a metallurgical melt and a slag layer covering it comprises producing a flow in the reaction zone between the two liquids of different specific gravities such that the liquid of high specific gravity, for example, the melt is circulated in the vessel and guided substantially radially outwardly in the reaction zone whereas the liquid of low specific gravity, for example, the slag, is conveyed in a circulation from the periphery inwardly in substantially opposite direction to that of the high specific gravity liquid.

. A device for carrying out the method includes two pumping elements, one of which takes suction at the lower end of the liquid of high specific gravity and circulates this liquid upwardly to the reaction zone in the vicinity of the level of the liquid of low specific gravity and directs outwardly toward the outer periphery of the reaction zone. A second pumping element is arranged to take suction at the outer periphery of the liquid of low specific gravity and to direct it inwardly at a location adjacent the level of the high specific gravity. A pump construction for this purpose may -advantageously include a single rotor mounting an impeller having an elongated cylindrical suction extending downwardly into the high specific gravity melt and an upper portion extending radially outwardly and having peripheral openings for discharging the high specific gravity liquid radially outwardly. The same pump shaft also carries an impeller at the upper end having vane elements which are curved in a formation for moving the low specific gravity liquid inwardly and for discharging it toward the center. The low specific gravity pumping impellers may advantageously be formed as blade elements on the top of the impeller for pumping the high specific gravity liquid.

PATENTED JAN 1 2197:

sum 2 OF 2 JAN 'Efl/K 05766106.

APPARATUS FOR IMPROVING THE REACTION BETWEEN TWO LIQUIDS OF DIFFERENT SPECIFIC GRAVITIES SUMMARY OF THE INVENTION This invention relates, in general, to a method and apparatus for improving the reaction between two liquids in a metallurgical reaction vessel and, in particular, to a new and useful method for improving the circulating flow in the reaction zone between two liquids of different specific gravities and to a pumping device for producing such flow.

The invention is particularly applicable for improving the reaction characteristics of metallurgical furnaces of a type in which the reaction vessel or furnace contains two liquids of different specific gravities and at high temperature within the same vessel. The invention deals in particular with the formation of a flow in and to the boundary surface of a metal melt and a layer of sla'g or a mixture of metal and slag lying thereabove. A flow in the reaction zone is of advantage when a treatment between the metal melt and the slag layer covering it is desired or where a treatment between one layer of the melt and another layer of a different specific gravity and different flow characteristics is desired. It is desirable that the flow in the reaction zone be such as to cause the reaction to occur in a short time and to affect the entire melt. For small melt weights, manually guided agitators may be sufficient for this purpose, but this is not possible with great melt weights.

For such weights, one must employ either electromagnetic agitators or motor-driven stirring devices.

In accordance with the present invention, it has been found that a considerable shortening of the reaction time can be obtained between two liquids of different specific gravities if the relative velocity between the liquids is increased and provision is made to insure that substantially the entire quantity of the one liquid is brought into contact with the substantially entire quantity of the other. It has also been found desirable to insure that a turbulent flow of the both liquids occurs in the reaction zone and that the total quantities of the various liquids come into contact with one another in a very short time.

A determining factor for the reaction velocity is also the size of the reaction zone. If a pump is used for circulating the various liquids an area corresponding to the cross section of the pump is taken away from the reaction zone. Therefore, if it is desired to keep this reduction of the effective area very small and to maintain a radial flow over the entire surface of the interreacting liquids, the outflow velocity from the pump must be kept very high. Especially where separate jet pumps are concerned, this high velocity is essential for the whirling and turbulence in the reaction zone. Where a relatively thin layer is superimposed on a much thicker layer, the result is that the lighter layer tends to become entrained and collects on the walls of the vessel.

According to the present invention, the difficulties encountered by the prior art in respect to improving the reaction characteristics between two liquids of different specific gravities is solved by providing a pumping arrangement which is characterized by providing a circulation of the higher specific gravity liquid so that it is directed radially outwardly in the reaction zone whereas the layer of lower specific gravity liquid is entrained at a distance away from the reaction zone and conveyed centripetally inwardly in an opposite direction to the liquid of high specific gravity. In this manner, a reaction zone is insured in which substantially the total quantity of both layers is made to participate in the reaction.

It should be appreciated that the method of theinvention for improving the reaction between two liquids in a metallurgical reactor may be carried out by using any means to produce the flow conditions desired and, for example, two separate pumps or pumping elements may be employed. A particularly simple form of device for effecting the desired flow conditions, according to the invention, comprises two centrifugal pumps or pumping elements, one of which has a blade element designed so that it takes suction centrally from the lower end of the liquid of higher specific gravity and directs this liquid upwardly and then radially outwardly at a location adjacent the level of the low specific gravity. The other pump takes suction at the outer periphery at a locationsurrounding the reaction zone of the low specific gravity liquid and directs it centripetally inwardly. A single rotatable pump element with the two separate pumping parts is advantageous to provide a desirable circulation of a melt in a metallurgical furnace, for example, between the upper slag layer and the lower melt layer. Such a pumping element comprises a central tubular portion which takes suction at the lower end of the heavier specific gravity liquid and includes impeller vanes connected to the central suction for directing this liquid radially outwardly at a location of the reaction zone. A further pumping element is defined by separate slag-impellers or blade elements above the impeller vanes for'directing the flow of the slag from an outer peripheral location around the reaction zone centrally inwardly.

Accordingly, it is an object of the invention to provide a method of improving the reaction between liquids of different specific gravities, for example, between a slag layer and a melt in a metallurgical reactor which comprises forcefully circulating the liquid of heavier specific gravity outwardly adjacent the layer of low specific gravity and simultaneously circulating the liquid of lower specific gravity from a location around the periphery of the reaction zone inwardly.

A further object of the invention is to provide a device or arrangement with a formation of flow in a reaction zone between two liquids of very different specific gravities which are containedin a vessel and, in particular, for the boundary surfaceof a metal melt and a slag layer comprising pumping means for pumping liquid of high specific gravity upwardly from the center of the liquid and outwardly in the reaction zone, and pumping means for pumping the liquid of low specific gravity inwardly in the reaction zone.

A further object of the invention is to provide a metallurgicalreactor having a rotatable pumping element with a suction extending downwardly into a liquid of low specific gravity and impeller means for directing the liquid radially outwardly and second impeller: means located above the first impeller in a position to direct the liquid of low specific gravity inwardly in the vicinity of the boundary between the two liquids.

A further object of the invention is to provide a metallurgical furnace device for circulating liquids of two different specific gravities of a melt which is simple in design, rugged in construction and economical to manufacture.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings;

FIG. 1 is a longitudinal section throughfa crucible having a circulating pump constructed in accordance with the invention;

FIG. 2 is a section taken along the line II-lI of FIG. 1; and

FIG. 3 is a view similar to FIG. 1 of another embodiment of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, in particular, the invention embodied therein in FIGS. 1 and 2 comprises a metallurgical crucible l which is filled with a liquid or melt 20, for example, a steel melt up to a level line 2. Above the level line 2, the crucible contains a layer of a liquid of a lower specific gravity 5 or a slag layer 3.

' In accordance with the invention, circulating means, generally designated 22, are provided for forming a desired flow in the reaction zone between the high specific gravity liquid 20 and the low specific gravity liquid 3. In the embodiment illustrated, the circulating means 22 comprises a first pump or first impeller 4 having a central suction formed as an elongated tube 5 with a suction opening Saat its lower end for taking suction in the liquid of high specific gravity 20 adjacent the lower end of the crucible 1. The impeller 4 includes a cylindrical part 4a having a plurality of apertures or discharge opening 7 through which the liquid 20 is directed so that it is moved radially outwardly toward the outer walls of the crucible. Both the impeller 40 and the tubular part are advantageously made of a refractory ceramic material and they are affixed to the lower end of a shaft 8 which is held mounted and driven by means (not shown). The mounting of the shaft 8 is such that it may be adjustably positioned to the desired position indicated at which the impeller cylindrical part 40 is locatedjust below the level 2.

The shaft 8 is rotated at a speed to drive the circulating means 22 fast enough to cause the melt liquid to be drawn in through the suction 5a and moved upwardly through the impeller 4 and discharged out through the openings 7 at a speed which causes the continued movement of the liquid 20 up to the walls of the crucible l. The great speed which is required to move the heavy melt into the reaction zone produces a reaction promoting turbulence. However, at the necessary speed required, the slag layer 3 would also be entrained and be removed from the reaction zone unless means were provided to circulate it back into the reaction zone. Such means comprises a slag impeller or second pump generally designated 9 which includes a plurality of circumferentially spaced spirally formed or sickle-shaped vanes 13 which are secured to a hub portion 10 which is affixed to the shaft 8 for rotation therewith. Each impeller blade 13 is moved by rotation of the shaft 8 in a direction to entrain the slag liquid 3 and direct it inwardly as indicated by the arrows of FIG. 1 and to discharge it at a discharge opening 14 centrally within the crucible 1 in the reaction zone directly adjacent the level 2. The blades 13 are designed so that a centripetal movement is produced so that the slag is conveyed from the periphery toward the axis of rotation. The lighter slag layer 3 is thus continuously circulated in the reaction zone adjacent the liquid level line 2. To insure the centripetal movement the blades 13 must be specially designed. The condition for such a design. may be expressed mathematically as follows:

u c must be less than V1 211 where: u is the rotational speed at any point of the blade, u, is the rotational speed in a point on the blade which lies between u and the hub, and c, is the projection of the absolute velocity of the liquid in the direction of the rotational speed in the point where the rotational speed is 14,, and c is the projection of the absolute velocity of the liquid in the direction of the rotational speed in the point where this rotational speed is u Generally, this simple arrangement outlined above is sufficient. The rotation of the impeller. blades causes the inward movement of the slag liquid 3 surrounding the periphery of the blades. In some instances, the blades 13 are bounded by upper and lower discs 11 and 12, respectively. This construction is applied especially when the stress on the material is not too great and, in this event, the slag 3 is delivered through the discharge 14 downwardly below the plate 12 and adjacent the. level 2 at the vicinity of the hub 10. The blades 13 have the general angular formation indicated in FIG. 2 however, special hydrodynamic properties of the particular liquid employed will influence the selection of the blade angle.

In the embodiment indicated in FIG. 3, a circulation movement is produced for a lighter slag layer 3' using circulating means generally designated 2 2. The circulation means 22' comprises a tubular member or suction pipe. 16 having an inlet or suction 160 at the lower, end and which is connected at its upper end to an impeller 11 having discharge passages l7a which are inclined upwardly to a discharge 17b The impeller 17 and the suction pipe 16,are carried at the end of a shaft 8' which is driven and supported by rotation means (not shown). The shaft 8' is rotated at a speed such that the liquid melt 20 will be drawn upwardly to the inlet l6aand conveyed radially outwardly through thepassages 17a as indicated by the arrows. The level of the melt 20 will rise toward an outer wall 10'. The entrained outer slag layer 3" which is lighter than the layer 20' will rise at the outer periphery adjacent the wall la and will flow back in its upper part in the direction of the arrow indicated toward the axis of the shaft 8. The centrifugal outward flowing of the lighter slag layer 3' can be supported by fins or blades 15 arranged on the impeller elements 17. As favorable geometric conditions and suitable positions of the pump the suction pipe 16 may be omitted.

At certain speeds, the return flow of the slag 3 on the surface may be disturbed by too great a rotational speed and this may even lead to eddy formations. This disturbance is eliminated by a braking body 18 of a refractory material which extends downwardly from an overhead beam or support member 19.

While specific embodiments of the invention have been shown and described in detail to illustrate the application of the invention principles, it will be understood that the inven tion may be embodied otherwise without departing from such principles.

I claim:

I. A device for producing a circulating flow particularly in respect to a metal melt in a metallurgical reactor and at the location of a reaction zone defined between the contacting surfaces of two liquids of different specific gravity with the low specific gravity liquid floating on the surface of higher specific gravity liquid, comprising first flow producing means adapted to be located adjacent the reaction zone for moving the high specific gravity liquid from a central location below the reaction zone radially outwardly in the vicinity of the reaction zone, and second flow producing means adapted to be located adjacent the reaction zone for moving the liquid of low specific gravity from an outer peripheral location inwardly in the vicinity of the reaction zone.

2. A device for producing a circulating flow particularly in respect to a metal melt in a metallurgical reactor and at the location of a reaction zone defined between the contacting surfaces of two liquids of different specific gravity with the low specific gravity liquid floating on the surface of the higher specific gravity liquid, comprising first flow producing means adapted to be located adjacent the reaction zone for moving the high specific gravity liquid from a central location below the reaction zone radially outwardly in the vicinity of the reac tion zone, and second flow producing means adapted to be located adjacent the reaction zone for moving the liquid of low specific gravity from an outer peripheral location inwardly in the vicinity of the reaction zone, said first and second flow producing means including means for moving in the liquid of low specific gravity radially and centripetally inwardly and for discharging the liquid of lower specific gravity in an inner central location for return flow outwardly directly above the level line of the two contacting liquids.

3. A device, according to claim 1, wherein said flow producing means includes means for taking suction in the liquid of high specific gravity for moving it upwardly and then outwardly intothe vicinity of the reaction zone.

4. A device, according to claim 1, wherein said first flow producing means includes means for directing the liquid of high specific gravity upwardly and outwardly in the vicinity of the reaction zone.

5 A device for producing a circulating flow particularly of the melt in a crucible of a metallurgical process which requires a reaction between two liquids of different specific gravity having their surfaces in contact with the lower specific gravity liquid floating on the surface of the higher specific gravity liquid, comprising a first pump having a first rotatable impeller adaptedto be located in the liquid of high specific gravity and including a central suction for the intake of the liquid of high specific gravity and a radial discharge for discharging the liquid of high specific gravity radially outwardly in the vicinity of the reaction zone and a second pump adapted to be located in the liquid of low specific gravity and having means for drawing the low specific gravity inwardly and discharging it in. a centralarea adjacent the reaction zone.

6. A device, according to claim 5, wherein said first pump includes an elongated suction pipe adapted to be extended downwardly into the high specific gravity liquid for taking suction at a a location remote from the reaction zone;

7. A device, according to claim 5, wherein said second pump includes a plurality of impeller blades of generally curved formation shaped to draw the liquid of low specific gravity radially inwardly and to discharge it centrally of the reaction zone. p

8. A device, according to claim 5, wherein said first pump includes a central suction and an impeller connected to said suction and extending radially upwardly and outwardly from said suction for delivering the liquid of high specific gravity radially upwardly and outwardly.

9. A device, according to claim 5, where said first impeller includes a conically shaped portion having a central suction a suction pipe connected to said conically shaped portion and adapted to extend downwardly into the liquid of high specific gravity, and a cylindrical discharge section adapted to receive liquid pumped through the central suction and into said first impeller and having a plurality of openings therein for discharging said high specific gravity liquid outwardly and upwardly into the reaction zone.

10. A device, according to claim 5, wherein said first rotary impeller includes upwardly and radially outwardly extending passage defining blade means with a central suction adapted to be located in the high specific gravity liquid forming said first pumping means, said blade means formed on the exterior of said impeller forming said second pumping means, said impeller with said blade means being rotatable to produce a central rotatable vortex cavity and a surrounding higher level of both liquids, said blade means being such as to produce a radial outward flow of the lower density liquid at a location adjacentthe contacting surfaces of said higher and lower specific gravity liquids.

11. A device, according to claim 5, including a rotatable shaft adapted to be positioned in a crucible having the high and low density liquids, said first pumping means including an impeller section connected to the inner end of said shaft at a location below the contacting surface level of the two liquids and having a central suction, and means extending radially upwardly from said suction and outwardly at a plurality of locations defining discharge passages for the liquid of high specific gravity, and blade elements defined on the upwardly and outwardly extending exteriors of said impeller shaped to produce an outward rotational flow of the lower density liquid when the rotation is sufficient to causea vortex inner flow around said impeller and a raising of the level surrounding said impeller. 

2. A device for producing a circulating flow particularly in respect to a metal melt in a metallurgical reactor and at the location of a reaction zone defined between the contacting surfaces of two liquids of different specific gravity with the low specific gravity liquid floating on the surface of the higher specific gravity liquid, comprising first flow producing means adapted to be located adjacent the reaction zone for moving the high specific gravity liquid from a central location below the reaction zone radially outwardly in the vicinity of the reaction zone, and second flow producing means adapted to be located adjacent the reaction zone for moving the liquid of low specific gravity from an outer peripheral location inwardly in the vicinity of the reaction zone, said first and second flow producing means including means for moving in the liquid of low specific gravity radially and centripetally inwardly and for discharging the liquid of lower specific gravity in an inner central location for return flow outwardly directly above the level line of the two contacting liquids.
 3. A device, according to claim 1, wherein said flow producing means includes means for taking suction in the liquid of high specific gravity for moving it upwardly and then outwardly into the vicinity of the reaction zone.
 4. A device, according to claim 1, wherein said first flow producing means includes means for directing the liquid of high specific gravity upwardly and outwardly in the vicinity of the reaction zone.
 5. A device for producing a circulating flow particularly of the melt in a crucible of a metallurgical process which requires a reaction between two liquids of different specific gravity having their surfaces in contact with the lower specific gravity liquid floating on the surface of the higher specific gravity liquid, comprising a first pump having a first rotatable impeller adapted to be located in the liquid of high specific gravity and including a central suction for the intake of the liquid of high specific gravity and a radial discharge for discharging the liquid of high specific gravity radially outwardly in the vicinity of the reaction zone and a second pump adapted to be located in the liquid of low specific gravity and having means for drawing the low specific gravity inwardly and discharging it in a central area adjacent the reaction zone.
 6. A device, according to claim 5, wherein said first pump includes an elongated suction pipe adapted to be extended downwardly into the high specific gravity liquid for taking suction at a a location remote from the reaction zone.
 7. A device, according to claim 5, wherein said second pump includes a plurality of impeller blades of generally curved formation shaped to draw the liquid of low specific gravity radially inwardly and to discharge it centrally of the reaction zone.
 8. A device, according to claim 5, wherein said first pump includes a central suction and an impeller connected to said suction and extending radially upwardly and outwardly from said Suction for delivering the liquid of high specific gravity radially upwardly and outwardly.
 9. A device, according to claim 5, where said first impeller includes a conically shaped portion having a central suction a suction pipe connected to said conically shaped portion and adapted to extend downwardly into the liquid of high specific gravity, and a cylindrical discharge section adapted to receive liquid pumped through the central suction and into said first impeller and having a plurality of openings therein for discharging said high specific gravity liquid outwardly and upwardly into the reaction zone.
 10. A device, according to claim 5, wherein said first rotary impeller includes upwardly and radially outwardly extending passage defining blade means with a central suction adapted to be located in the high specific gravity liquid forming said first pumping means, said blade means formed on the exterior of said impeller forming said second pumping means, said impeller with said blade means being rotatable to produce a central rotatable vortex cavity and a surrounding higher level of both liquids, said blade means being such as to produce a radial outward flow of the lower density liquid at a location adjacent the contacting surfaces of said higher and lower specific gravity liquids.
 11. A device, according to claim 5, including a rotatable shaft adapted to be positioned in a crucible having the high and low density liquids, said first pumping means including an impeller section connected to the inner end of said shaft at a location below the contacting surface level of the two liquids and having a central suction, and means extending radially upwardly from said suction and outwardly at a plurality of locations defining discharge passages for the liquid of high specific gravity, and blade elements defined on the upwardly and outwardly extending exteriors of said impeller shaped to produce an outward rotational flow of the lower density liquid when the rotation is sufficient to cause a vortex inner flow around said impeller and a raising of the level surrounding said impeller. 